Front Cover: The Dynamic Range of Acidity: Tracking Rules for the Unidirectional Penetration of Cellular Compartments (ChemBioChem 15/2022)

Changing color like lobsters during cooking, flipper probes with cationic acids are introduced to elucidate the mechanics of early endocytosis, and to reveal universal tracking rules for unidirectional penetration along transmembrane pH gradients. Consistent with a dynamic range of Delta pK(a)=3.5 for temporary deprotonation, cationic acids with pK(a)=9.8 stay only within more acidic early endosomes (pH similar to 6.3), while those with pK(a)=10.6 track also the less acidic ones (pH similar to 6.5). For these early endosomes, cationic acids with pK(a)=7.4 are too acidic for retention, those with pK(a)=13.5 are too basic for penetration. More information can be found in the Research Article by S. Matile et al.

Automated summary

By using flipper probes with cationic acids, researchers have elucidated the mechanics of endocytosis and revealed universal rules for unidirectional penetration along pH gradients.